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small applet version

	Select your time zone offset.
	Enter latitude in decimal degrees, and press return key, enter longitude in decimal degrees, and press return key.

 

The vertical shadow-casting gnomon is placed on the North-South line depending on the current date. The time is read from the intersection point of the shadow and the ellipse: The height H of the gnomon necessary for the shadow to intersect the ellipse even at summer solstice depends on the observer's latitude. For an ellipse having the major semiaxis a we get latitude H 50° 0.97 a 40° 1.04 a

The sundial at my home location (51.62° N, 7.97° E)
2003, June 29 at 12:15 CET
Equation of time is -3m 22s
(sundial is slow, add 3m 22s to the time read from the sundial to get the mean local time)

Use a compass to align the sundial north-south (correction for magnetic declination)
(for my home location the magnetic declination is only 0.1°)

at 15:00 CET

	The figure "8" shape is known as the "analemma". It visualizes the equation of time.
	The Java console shows the coordinates (X,Y) of the hour points and a table of of the equation of time (for 2002) and the date points (0,Y):

Sundials for special locations
(North Pole, Arctic Circle, Tropic of Cancer, Equator)

More of my sundials:

Pie Sundial

Analemma Sundial

Web Links

Analemmatic sundials: How to build one and why they work (C.J. Budd and C.J. Sangwin) Compute Values of Earth's Magnetic Field (NOAA/NGDC) Analemmatic Sundial Functions (John Carmichael) Of Analemmas, Mean Time, and the Analemmatic Sundial (Frederick W. Sawyer) Make your own Sundial

Last update: 2010, Oct 10